Clearview National December 2016 - Issue 181 | Page 36

BI-FOLDING&SLIDINGDOORS

When is a PVCu bi-fold
not a PVCu bi-fold?
“One of the most satisfying things is to see the
look on new customers’ faces when they try
the ModLok™ bi-fold for the first time!”
»»SO SAYS DESIGN AND DEVELOPMENT
Manager, Chris Armes, who has more reason
than most to be happy with this reaction
– he was an integral part of the ModLok’s
innovative design.
Clearview found out what makes this bifold completely different from the other PVCu
systems on the market, and exactly why Liniar
customers are so delighted with the door…
HISTORIC PROBLEMS WITH PVCU
When PVCu bi-folds first appeared,
they seemed to offer a cost effective way of
meeting the demand for this new must-have
door system. However, it didn’t take long for
problems to arise, with the new systems falling
foul of expansion and contraction issues, size
and weight stresses and hardware failures resulting in expensive call-backs and repairs.
Any installer experiencing these problems
first-hand might be forgiven for steering well
clear of PVCu bi-folding doors ever since. But
PVCu is still a great material to use, not only
for its thermal properties but to match fully
with the rest of the installation.
FRESH, NEW APPROACH TO
A PATENTED DESIGN
By taking a fresh new approach, looking
at the inherent issues with PVCu and testing
ways to overcome problems, Chris and the
Liniar team were able to launch a brand new
patented concept, as he explains:
“The sheer size of a bi-fold door meant
PVCu frames needed steel reinforcement to
support the weight of the glazed units. But by
adding steel, the doors lost thermal efficiency,
with cold air being transferred – so U-values
were poor.
“In addition, and in spite of the steel
reinforcement, early PVCu doors were unable
to span large heights or widths. The weakness of
PVCu meant that the continued opening and
closing of bi-folding doors eventually led to faults
with hinges, rollers and other moving parts, due
to the movement that the profiles allowed.”

36 » DEC 2016 » CL EARVI E W- UK . C O M

TURNING IT
INSIDE OUT
“We wanted to put
the reinforcement
on the outside of the
PVCu, rather than the
inside,” continues Chris,
“but this hadn’t been done
before, as it interfered with the
positioning of the locks.
“So we designed our own unique locking
system and embedded it into an aluminium
exoskeleton which encased the PVCu (hence
the name, as it’s literally a modular locking
system). This not only bypassed the problem
but led to a much improved and more secure
bi-fold.
“It’s not usually possible for hinges to be
secured directly to the doors’ reinforcement;
however, the ModLok™ concept enabled
this innovation to become reality, which was
beneficial for PAS:24 testing. This means we’ve
achieved both PAS:24 and Secured by Design
compliance with ease.”

‘U-values of 1.0 achievable
with triple glazing’
THERMALLY EFFICIENT
“The other benefit to using aluminium on
the exterior meant that additional PVCu webs
could be added inside the profile, or frames.
This results in multiple chambers of air inside
each profile, improving energy performance
and making U-values of 1.0 achievable with
triple glazing.”
CYCLE TESTING
“All the indications showed the aluminium
exoskeleton would give the doors unparalleled
stability and durability - however this
needed to be cycle tested,” says Chris. “So
we purchased an ABB articulated robot and
tested a full-size 3-pane ModLok™ bifold on a
custom-built rig.”

“Our robot eventually reached hit 128,700
full ‘open and close’ cycles before we stopped
it to test our next product - with the ModLok
bi-fold still fully operational. This was
more than 12 times the British Standard
required for a door of this type, so we knew it
worked!”
HIGH STRENGTH AND
LARGE SIZES
“The ModLok™ categorically isn’t a
hybrid - it has a core of PVCu profiles
with an aluminium surround - so it’s very
straightforward for Liniar fabricators to
manufacture,” continues Chris.
“Its strength and rigidity are almost
equivalent to that of an aluminium bi-folding
door, giving us confidence in the maximum
sizes of 2.1m high by 1.0m wide sashes and
up to 7 panes wide.”
ISSUES SOLVED
Best of all, the ModLok™ has put to rest the
previous issues with PVCu bi-folds; we haven’t
had a single fault reported since its launch.
When new customers see it in our showroom,
they often don’t realise it’s made from PVCu,
as it operates so smoothly,” concludes Chris.
www.liniar.co.uk